Besides delectability, their flavors are derived in part from terroir, a loanword from French which roughly means “a sense of place.” From a scientific standpoint, terroir refers to the combined effects of geography, soil, local climate, and plant genetics on certain agricultural products. French winemakers put great stock in terroir, though not all of their American peers have been sold on the idea. There’s little data to define what terroir is. Testing the concept is incredibly difficult—there are almost too many potential variables.

Wines are said to get some of their flavor from terroir, or the peculiarities of the region in which its grapes are grown.

But now, DNA analysis appears to have nailed down at least one part of the terroir equation. A research team led by David A. Mills and Nicholas A. Bokulich of the University of California, Davis sampled grape musts—the mashed grapes that are the starting point for making wine—and discovered that different grape varieties carry distinct patterns of fungi and bacteria.

Here’s Nicholas Wade, writing for The New York Times:

They found, for instance, that one set of microbes is associated with chardonnay musts from the Napa Valley, another set with those of a must in Central Valley and a third grouping with musts from Sonoma. They noticed a similarly distinctive pattern of microbes in cabernet sauvignon musts from the north San Joaquin Valley, the Central Coast, Sonoma and Napa.

The discovery of stable but differing patterns of microbial communities from one region’s vineyards to another means that microbes could explain, at least in part, why one region’s zinfandel, say, tastes different from another’s. The links between microbes and wine-growing regions “provide compelling support for the role of grape-surface microbial communities in regional wine characteristics,” the researchers conclude.

The scientists still need to prove whether or not these microbes influence the quality of the wine. Scientists are excited to continue this research, though even Mills admits that there’s an argument for holding off. “Many people don’t want this figured out,” he tells Wade, “because it demystifies the wonderful mystery of wine.”